FIG. 1 is a side sectional view of a general drier, and FIG. 2 is a plan view of the general drier.
Referring to FIGS. 1 and 2, the drier has an outer case 53 defining an outer shell thereof. A front plate 41 is connected to the leading end of the outer case 53 so as to form the front face of the drier. A drum 44 is rotatably installed inside the outer case 53 such that laundry is loaded into and dried in the drum 44. The drum 44 is rotated by a drum-drive belt 54 which surrounds the outer surface of the drum 44.
An exhaust hole 43 is formed to correspond to an inner surface of the front plate 41 and be opened toward the inside of the drum 44. The exhaust hole 43 functions to exhaust air out of the drum 44. A lint filter 36 is disposed at an entrance of the exhaust hole 43 so as to remove foreign particles contained in air.
At a portion of the exhaust hole 43, an electrode sensor 38 is disposed for detecting the dryness of laundry within the drum 44 while the laundry is dried. The electrode sensor 38 detects the dryness of laundry based upon a difference of voltages applied to both end terminals of the electrode when the laundry is in contact with the electrode 38. The electrode sensor 38 provides a microprocessor 100 with a detection signal in the form of a voltage signal. An exhaust passage 45 is placed inside the front plate 41 so as to be connected with the exhaust hole 43. A blower assembly 30 is installed so as to communicate with the exhaust passage 45. The exhaust passage 45 includes a second temperature sensor 32 for detecting the temperature of air which is exhausted out of the drum 44.
The blower assembly 30 is connected to an exhaust duct 34 for discharging air which is exhausted via the exhaust passage 45 out of the drier. The blower assembly 30 includes a blower 31 which sucks and circulates air into/in the drum 44 to introduce heat of a heater 42, and discharges moisture from laundry via the exhaust hole 43.
A feed duct 46 to feed air into the drum 44 is disposed at a portion within the outer case 53 and corresponding to a lower portion of the drum 44. The feed duct 46 feeds air into the drum 44 via a rear portion of the drum 44. A heater 42 is disposed adjacent to a portion of the feed duct 46. A temperature sensor 48 to detect the temperature of air sucked into the drum 44 is disposed in another portion of the feed duct 46.
FIG. 3 is a block diagram of components used in controlling the general drier.
A mainboard 52 is disposed in a portion within the outer case 53 so as to electrically control the operation of the drier. The mainboard 52, as shown in FIG. 3, includes a microcomputer 100 for generally controlling a drier, a drive unit 120 for driving components which should be electrically controlled within the drier, and a group of sensors 110 for detecting electric signals so as to judge the operational status of the drier.
The group of sensors 110 include: a key input unit 103 for providing the microcomputer 100 with a power supply signal, a drying operation signal and drying conditions which are selectively inputted by a user; an electrode sensor signal conversion unit 106 for converting a signal detected by the electrode sensor 38 into a signal readable by the microcomputer 100 and providing the converted signal to the microcomputer 100 so as to detect the current dryness of laundry; a first temperature sensor signal conversion unit 109 for converting a signal detected by the first temperature sensor 48 into a signal readable by the microcomputer and providing the converted signal to the microcomputer 100 so as to detect the temperature of hot air fed into the drum 44; a second temperature sensor signal conversion unit 112 for converting a signal detected by the second temperature sensor 32 into a signal readable by the microcomputer 100 and providing the converted signal into the microcomputer 100 so as to detect the temperature of hot air exhausted from the drum 44; and a door detection unit 115 for detecting the opening of a door while laundry is being dried, converting a result of the detection into a signal readable by the microcomputer 100 and providing the converted signal to the microcomputer 100.
The drive unit 120 includes a drum motor drive unit 118 for driving a drum motor (not shown) which generates driving force for rotating the drum 44, a blower motor drive unit 121 for generating driving force for rotating the blower 31 and a heater drive unit 124 for supplying heat source for drying laundry via the feed duct 46.
FIG. 4 illustrates a construction of the second temperature sensor signal conversion unit shown in FIG. 3.
Referring to FIG. 4, when the electrode sensor 38 is in contact with laundry circulating within the drum 44, the resistance value of the electrode sensor 38 is varied depending upon the dryness of laundry. The microcomputer 100 measures the dryness of laundry by receiving the resistance valve of the electrode sensor 38 varied with the dryness of laundry and a voltage divided by a resistor R1.
A dryness measuring device having the electrode sensor 38 and the resistor R1 uninterruptedly outputs detection values regardless of a time point of when the microprocessor 100 detects the dryness, and the detection values are continuously inputted into the microcomputer 100. The microcomputer 100 measures the dryness based upon the detection values which are inputted before and after the time point of a dryness measurement and which are currently being inputted. In other words, at the time point of measurement, the dryness is influenced by the detection values before and after the time point of the dryness measurement.
For example, where the electrode sensor 38 has a resistance value variable under the external influence, the resistance value is directly applied to a detection value, which may be used in dryness measurement together with other detection values which are being continuously detected. As a result, the microprocessor 100 fails to precisely measure the dryness owing to the resistance value which is under the external influence at the time point of the measurement.